Nano research eyes ink jet-printed 'sheets' of circuits

Portland, Ore. - NanoProducts Corp. lab researchers have begun work on nanoscale devices that may lead to the formation of "plastic" circuit elements and circuit "sheets" fabricated with ink jet printers within three years. The company's researchers have started the evolution toward such products by integrating nanoscale materials with existing micron-sized devices and composites, enhancing their performance and lowering their cost.

"The first generation of nanotechnology will just be performance enhancements to existing micromaterials-significant performance enhancements-but it's the second generation, in about three years, that will start employing nanomaterials in much more significant quantities," said Tapesh Yadav, chairman and CEO of NanoProducts (Longmont, Colo.).

"We can make nanoscale materials conducting or insulating or magnetic or with any of the properties that electrical engineers use to build devices, like dielectrics. We have a dielectric powder you could make capacitors with," said Yadav. He said the company's subsidiary research lab is making actual devices like capacitors, inductors and resistors using technology based on its patents. "Just making the powder is not good enough; you have to know how they perform, so you can learn from that."

In the Joule-Quench process, a combustion of a precursor creates a stream that is heated into a plasma exceeding 3,000 K, after which cooling leads to nucleation (formation of nanoparticles). Sonic quenching is used to eliminate "sticky" collisions, thereby producing a steady stream of nanopowders.

According to Yadav, those materials are already being incorporated into current devices to enhance the characteristics of micron-sized materials. As proof, Yadav pointed to a recent Fuji Photo Film Co. Ltd. announcement of its NanoCubic material that could be used to store 3 Gbytes on 3 1/2-inch floppy disks. The under-50-nanometer nanoparticle material has a magnetic coating that enhances density but can be 10 times thinner than traditional iron oxides.

"When you add barium to iron oxides, you change the magnetic properties at the nanoscale, giving you the ability to go to higher densities," said Yadav.

NanoProducts makes barium-ferrite particles that are less than 50 nm in diameter. The lab has learned how to combine the particles with a resin that could be used to apply a uniform film of barium ferrite on tape, disks or magnetic strips.

Conducting oxides that simplify the manufacture of flat-panel displays while enhancing their performance are another hot area for nanoscale enhancements, according to the lab. For instance, a conducting yet transparent oxide eliminates opaque metallization layers now necessary to address pixels in flat-panel displays. Transparent electrodes, according to Yadav, enable smaller, cheaper and higher-performance displays and solar cells.

"Our requirements were that the material must be conducting and transparent and be very thin, because it must be very light," Yadav said, "Only nanomaterials have the capabilities to enable these kinds of characteristics."

Dispersions currently available from NanoProducts include doped and undoped dielectrics, conductive and magnetic compositions, electrochemical materials, and rare earths.

The dispersions have been successfully incorporated into patterned films that are essentially transparent, yet offer significantly improved conductive patterning, according to Yadav. NanoProducts' nanoparticle dispersions can be used to print patterned layers of functional materials for flat-panel displays such as active-matrix liquid-crystal displays, plasma displays, electroluminescent displays, organic light-emitting displays and field emission displays, he said.

It's the synergy with micron-sized materials, however, that drives nanoscale materials research, Yadav said. For instance, ink toners, when properly formulated at the nanoscale, can provide first- and last-printed pages that look identical. Current toners settle, so fading occurs as the cartridge ages.

"We provide the nanomaterials and dispersion, so that if it is ink they can print it, or if they want they can make devices from it, or if it is composites we can provide the formulations," said Yadav.

For the future, the lab is working on a variety of traditional electronic devices based on nanoscale materials that will enable them to be printed with ink jet printers or incorporated into layered composites.